Dewaxing process



Oat. 19, 1943. J. v. MONTGOMERY ET AL 2,331,993 DBWAXING rnoczss Original Filed Sept. 50, 1940 LOWERING OF M lSCib:L.ITY TEMPERATURE F G 2 4 s 6 l0 I2 PERCENT MATERIAL ADDED TO PICOLJNE SOLVENT PERCENT BY VOLUME J, v MONTGOMERY L. a. GOODSON .w. HENRY INVENTORS BY Mm.,? 7

ATTORNEYS Patented Oct. 19, 1943 UNITED STATES PATEN T forties? DEWA'XING Paoc'Ess James V. Montgomery, Fort Huachuca, Ariz., Luke B. Goodson, Phillips, .Tex., and '.:Robert W. Henry, Bartlesville, 0kla., assignors to Phillips Petroleum Compan aware y, a corporationof Del- Original application September 30, 1940, Serial 1 No. 359,164. Divided and this application August 10, 1942, Serial No. 454,320

4 Claims. (Cl. 196-18) This invention relates to mineral oil refining, and more particularly it relates to an improved dewaxing solvent.

This application is a divisionoi our copending application, Serial No. 359,164, filed September 30, 1940, now Patent No. 2,303,570, dated December 1, 1942. v

It is known to use heterocyclic nitrogen base compounds suchas pyridine, picolines, lutidine s,

of lowering the miscibility temperature with I waxy oil, and assisting with the removal of water from the solvent system. These organic addition agents in order to exhibit maximum utility must possess boiling points below approximately 200 F., for example, it was suggested to add benzene, boiling point about 177 F., to the wet picoline solvent. Picolines and water form a physical mixture boiling at a constant temperature of approximately 200 F.

An object of this invention is to furnish an improved solvent for the dewaxing lubricating oil stocks.

Another object of this invention is to furnish a dewaxing solvent which has an increased tolerance for dissolved water.

Still other objects and advantages will be apparent from a study of the disclosure that follows. We now propose to improve the utility of picolines and similar solvents by adding thereto certain organic compounds which lower the miscibility temperature of the solvent with waxy oils, increase the dewaxing selectivity of the solvent, and which have higher boiling points than those specified in the above-mentioned application. These organic compounds are termed solubility enhancing agents. Our added solubility enhancing agents are in themselves selective and their presence in the solvent mixture not only lowers the miscibility temperature of the solvent and the oil to be dewaxed, but also increases the wax selectivity thereof. Since these compounds have higher boiling points they do not so readily assist in the removal of undesirable Water from the solvent system, but they do increase the tolerance of picolines and the like for water and thus improve the utility of the solvent. Compounds suitable for use according-to our in vention include such as:

Terpenes of the type of limonene, menthane, menthene, pinene, I d ,Alkylsulfides such as butyl, amyl sulfides,

Amines such as hexyl, heptyl amines, Mercaptans such as butyl, amyl, phenyl mercaptans,

Sulfur oils from gasoline caustic wash, Tiophene, and alkyl derivatives.

The figure shows the relation oithe miscibility temperature lowering and the amount of added material in the solvent. Referring to the figure, it is seen that a relatively small amount of limonene (percent by volume) added to a picoline solvent materially lowers the miscibility temperature of the oil-solvent mixture, for example 5% limonene in the picoline solvent lowers the miscibility temperature 10 F.

In another example, not shown on the accompanying graph, 5% limonene in a picoline solvent lowered the miscibility temperature of a waxy long residuum stock 9 F., from minus 14 F. to

minus 23 F.

Of the compounds tested, limonene, diamyl sulfide and amyl mercaptan were found to be the most efiective for lowering the miscibility temperature of the picoline-oil mixture.

In carrying out our invention, we do not wish to be limited by any special type of dewaxing apparatus, since essentially any standard dewaxing equipment should be satisiactory. For

dewaxing of the above mentioned long residuum stock at minus 20 F., the oil to be dewaxed is mixed with a picoline solvent containing 5% by volume (of the picoline solvent) oi limonene, and the mixture warmed to insure complete and rapid solution of the oil in the solvent mixture. The mixture is then chilled to said dewaxing temperature of say, minus 20 F., followed by filtration in any suitable type. of filter. Filtration is rapid since the wax crystals formed in this solvent mixture are distinct and sharp edged. The slack wax may be washed with additional solvent mixture at the dewaxing temperature to remove adhering oil solvent solution, and the combined filtrate solution and washings comprising dewaxed oil and solvent mixture are conducted to a solvent oil separating apparatus. This separating apparatus may comprise a conventional pipe heater and fractionating tower from which the solvent mixture is removed overhead as vapors and the oil exits from the lower portion thereof and is conducted to storage.

The solvent vapors from the above mentioned fractionator are condensed and the solvent mixture conducted to intermediate storage preparatory to reuse.

The used solvent mixture may contain a minute amount of moisture which had been extracted by the picoline solvent from theoiibeing dewaxed. Water tends to raise the miscibility temperature of a picoline and oil mixture, but to offset this increase in miscibility tempera ture, a quantity of limonene had previously been added. Hence, the addition of this" limonene had increased the toleration of the picoline solvent for water.

By occasional further additions .of such materials as above mentioned, an example being limonene, picoline solvents or similar solvents may be used for extended periods of time Without the necessity of having to be dehydrated or dried. Thus, the utility of picoline solvents is materially extended. a

While we have described the use of 'limonene in a picoline dewaxing'solvent, we do not wish to be limited in this manner since the materials or compounds heretofore mentioned function favorably in extending the utility of such solvents as the isomeric picolines, pyridine, -1utidines, collidines, etc., or mixtures of the same such as occur in commercial pyridine.

What we claim is? V l. The process of dewaxing mineral oils including the steps of mixing the waxy oil with a dewaxing solvent comprising picoline, and amyl mercaptan as a selective type solubility enhancing agent, which selective type agent increases the tolerance of the solvent mixture for water, chilling the oil-solvent mixture to precipitate the wax, and removing the precipitated wax.

.2. The process of dewaxing mineral oils ineluding the steps of mixing the waxy oil with a dewaxing solvent comprising a heterocyclic nitrogen base solvent, and amyl mercaptan as a solubility'enhancing agent, chilling the oil-solvent mixture to precipitate the wax, and removing the precipitated wax.

3. The process of dewaxing mineral oils including the steps of mixing the waxy oil with a dewaxing solvent comprising picoline, and amyl mercaptan as a solubility enhancing agent which increases the tolerance of the solvent mixture for water, chilling the oil-solvent mixture to precipitate the wax, and removing the precipitated wax.

4. The process of dewaxing mineral oils including the steps of mixing the waxy oil with a dewaxing solvent comprising picoline, and amyl mercaptan as a solubility enhancing agent, chilling the oil-solvent mixture to precipitate the wax, and removing the precipitated wax.

JAMES V. MONTGOMERY. LUKE B. GOODSON. ROBERT W. HENRY. 

